Trawsfynydd nuclear power station

Trawsfynydd nuclear power station (Welsh: Atomfa Trawsfynydd) is a decommissioned Magnox nuclear power station situated in Snowdonia National Park in Gwynedd, Wales. The plant, which became operational in 1965, was the only nuclear power station in the UK to be built inland, with cooling water that was taken from the man-made Llyn Trawsfynydd reservoir which also supplies the hydro-electric Maentwrog power station. It was closed in 1991. Its planned decommissioning by Magnox Ltd was expected to take almost 100 years,[1] but in 2021 the Welsh government arranged for the power station to be redeveloped using small-scale reactors.[2]

Trawsfynydd nuclear power station
Trawsfynydd Nuclear Power Plant.jpg
CountryWales, United Kingdom
LocationTrawsfynydd, Gwynedd
Coordinates52°55′29.51″N 3°56′54.38″W / 52.9248639°N 3.9484389°W / 52.9248639; -3.9484389Coordinates: 52°55′29.51″N 3°56′54.38″W / 52.9248639°N 3.9484389°W / 52.9248639; -3.9484389
Construction began1959
Commission date1965
Decommission date1991
Construction cost£103 million
Owner(s)Nuclear Decommissioning Authority
Operator(s)Magnox Ltd
Nuclear power station
Reactor typeMagnox
Reactor supplierAtomic Power Constructions
Power generation
Units decommissioned2 x 235 MW
External links
CommonsRelated media on Commons


The power station, which takes its name from the nearby village of Trawsfynydd, was designed by Basil Spence.[3] The construction, which was undertaken by a consortium involving Crompton Parkinson, International Combustion, Fairey Engineering and Richardsons Westgarth, and known as the Atomic Power Constructions (APC),[4] began in July 1959, and both of the reactors were in operation by March 1965, with the station opening fully in October 1968, at a cost of £103 million.[5] It had two Magnox reactors producing 470 megawatts (MW) in total.[5] The reactors were supplied by APC and the turbines by Richardsons Westgarth.[5] The civil engineering work was undertaken by Holland, Hannen & Cubitts[6] and Trollope & Colls.[7] The architectural consultant for the buildings was Sir Basil Spence and the landscape architect was Sylvia Crowe.[8]

Nuclear flasks were transported to Trawsfynydd on a section of the former Bala to Blaenau Ffestiniog railway that had been closed in January 1961. A single track was restored northwards with an entirely new line through the centre of Blaenau Ffestiniog that connected to the Conwy Valley branch. In 1963-64, a "Goliath" gantry crane was installed over sidings about 12 mi (0.80 km) east of the power station.[9][10][11][12] Beginning on 20 April 1964, nuclear flasks could be transported by rail between destinations such as Sellafield in Cumbria. The last regular departure was on 8 August 1995.[13] The last train to carry nuclear material from Trawsfynydd left on 22 April 1997 hauled by EWS Loco 37426.[14] The line was subsequently mothballed.[15] In 2016, enthusiasts, who want to create a heritage railway, began clearing vegetation along the route but have since been halted and are negotiating a new licence to clear.[16]


Trawsfynydd was shut down in 1991. The Nuclear Decommissioning Authority subsidiary Magnox Ltd is decommissioning the site. The work is expected to last decades.[17]

Beginning in 1993, the highly-radioactive spent fuel rods were removed from both Magnox reactors and sent by rail to Sellafield. This was completed in 1997. Intermediate level waste – such as on the walls of the cooling ponds or pipes – is being carefully removed using robots over the next decades. Contaminated material is stored in a specially-designed building on the site.[17] It will eventually be removed for deep burial in the UK's proposed geological disposal facility. Between 2020 and 2026, the top parts of the two reactor buildings were to be partially demolished to reduce their height,[18] but the steel reactor cores – that housed the fuel rods – will not be removed because they are still far too radioactive. The final clearance of the site is scheduled to begin in 2071.[18] By 2083, the area was expected to have been restored to its pre-nuclear state; 124 years after construction started and 92 years after the closure of Trawsfynydd power station.[1]


The Welsh government has decided to redevelop the plant using small-scale reactors, as a step toward meeting the UK's targets for reducing carbon emissions. In 2021, the government chose Mike Tynan of Westinghouse to lead a company tasked with developing the new reactors.[2] On 20 May 2022 the Government announced that the NDA will work with Cwmni Egino (the Welsh Development Agency company) to develop land adjacent to the site for a 300MW small modular reactor. Cwmni Egino said it will now discuss with interested parties and hoped to announce plans within one year.[19]

See alsoEdit


  1. ^ a b "So just how do you decommission a nuclear power station?". 30 December 2015. The plans call for the waste to be moved from Trawsfynydd in the 2040s.
  2. ^ a b "Wales advances its plans for small nuclear plants". Financial Times. 25 August 2021. Retrieved 17 September 2021.
  3. ^ Hirst, Clayton (December 21, 2009). "Pulling down Snowdonia's power station would be a nuclear waste". The Guardian.
  4. ^ "The UK Magnox and AGR Power Station Projects" (PDF).
  5. ^ a b c "". Archived from the original on July 19, 2009.
  6. ^ An historical survey of Cubitts, from the Company's inception in 1810 to the present day Page 25, Cubitts, 1975
  7. ^ "Trollope & Colls". National Archives. Retrieved 27 July 2019.
  8. ^ "Trawsfynydd Nuclear Power Station | Canmore".
  9. ^ "Railways of North Wales 1975-1983: blaenauffestiniog:Trawsfynydd Branch 1".
  10. ^ Mitchell & Smith 2010, Photo 28.
  11. ^ Southern 1995, p. 71.
  12. ^ "Llwytho fflasg Niwclear ar wagen reilffordd gorsaf bŵer Trawsfynydd 1993. Nuclear flask loading onto railway wagon Trawsfynydd power station 1993". January 23, 2013 – via Flickr.
  13. ^ "The last train of three flasks of spent fuel from the Trawsfynydd power station in 1995, seen here entering "Twnel mawr" in Blaenau Ffestiniog". December 28, 2015 – via Flickr.
  14. ^ Mitchell & Smith 2010, Photo 66.
  15. ^ "Inquiry into radioactivity scare". The Independent. 22 April 1997. Retrieved 9 August 2016.
  16. ^ "Clearance work on disused Trawsfynydd railway line to start". BBC News. 21 September 2016.
  17. ^ a b "How do you close a nuclear power station?". BBC. 28 October 2013. Retrieved 29 July 2016.
  18. ^ a b "So just how do you decommission a nuclear power station?". Wales Online. 30 December 2015. Retrieved 19 June 2017.
  19. ^ Owen Hughes (20 May 2022). "Nuclear Decommissioning Authority and Cwmni Egino announce plan for Trawsfynydd nuclear development". Business Live.
  • Mitchell, Vic; Smith, Keith (2010). Bala to Llandudno: Featuring Blaenau Ffestiniog. Midhurst, West Sussex: Middleton Press (MD). ISBN 978-1-906008-87-1.
  • Southern, D. W. (1995). Bala Junction to Blaenau Ffestiniog (Scenes from the Past, Railways of North Wales, No. 25). Stockport: Foxline Publishing. ISBN 1-8701-19-34-7.

External linksEdit